US7918938B2 - High temperature ALD inlet manifold - Google Patents

Abstract

A system and method for distributing one or more gases to an atomic layer deposition (ALD) reactor. An integrated inlet manifold block mounted over a showerhead assembly includes high temperature (up to 200° C.) rated valves mounted directly thereto, and short, easily purged reactant lines. Integral passageways and metal seals avoid o-rings and attendant dead zones along flow paths. The manifold includes an internal inert gas channel for purging reactant lines within the block inlet manifold

Description

RELATED APPLICATIONS

This application claims priority to Provisional Application No. 60/760,243, entitled HIGH TEMPERATURE ALD INLET MANIFOLD, filed on Jan. 19, 2006. The subject matter of the aforementioned application is hereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a manifold assembly for an atomic layer deposition (ALD) reactor.

2. Description of the Related Art

Atomic layer deposition (ALD) is a well known process in the semiconductor industry for forming thin films of materials on substrates such as silicon wafers. ALD is a type of vapor deposition wherein a film is built up through deposition of multiple ultra-thin layers with the thickness of the film being determined by the number of layers deposited. In an ALD process, gaseous molecules of one or more compounds (precursors) of the material to be deposited are supplied to the substrate or wafer to form a thin film of that material on the wafer. In one pulse, typically less than 1 monolayer of a first precursor material is adsorbed largely intact in a self-limiting process on the wafer. The adsorbed precursor material may be decomposed or otherwise reacted in a subsequent reactant pulse or pulses to form a single molecular layer of the desired material. For example, the adsorbed precursor material may react with the reactant of a subsequent reactant pulse to form a single molecular layer of an element or a compound. Examples include reactant pulses that merely strip ligands from the adsorbed species, reactants that replace ligands with other species to form compounds, and sequences with three or more reactant and/or precursor pulses per cycle. Thicker films are produced through repeated growth cycles until the target thickness is achieved.

In an ALD process, one or more substrates with at least one surface to be coated are introduced into the reactor or deposition chamber. The wafer is typically heated to a desired temperature above the condensation temperature but below the thermal decomposition temperature of the selected vapor phase reactants. One reactant is capable of reacting with the adsorbed species of a prior reactant to form a desired product on the substrate surface. The product can be in the form of a film, liner, or layer.

During an ALD process, the reactant pulses, all of which are typically in vapor or gaseous form, are pulsed sequentially into the reactor with removal steps between reactant pulses. For example, inert gas pulses are provided between the pulses of reactants. The inert gas purges the chamber of one reactant pulse before the next reactant pulse to avoid gas phase mixing or CVD type reactions. A characteristic feature of ALD is that each reactant (whether a precursor contributing species to the film or merely a reducing agent) is delivered to the substrate until a saturated surface condition is reached. The cycles are repeated to form an atomic layer of the desired thickness. To obtain a self-limiting growth, sufficient amount of each precursor is provided to saturate the substrate. As the growth rate is self-limiting, the rate of growth is proportional to the repetition rate of the reaction sequences, rather than to the flux of reactant and/or temperature as in CVD.

SUMMARY OF THE INVENTION

The systems and methods of the present invention have several features, no single one of which are solely responsible for its desirable attributes. Without limiting the scope of this invention as expressed by the claims which follow, its more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description of the Preferred Embodiments,” one will understand how the features described herein provide several advantages over traditional ALD mixing methods and systems.

One aspect is an atomic layer deposition device. The device comprises a manifold body having a first passageway and a second passageway, the first passageway and the second passageway having no o-rings. The device further comprises a bore located within the body and in flow communication with the first passageway and the second passageway. The device also comprises a vapor deposition chamber in flow communication with the bore and configured to deposit a thin film on a wafer mounted therein.

Another aspect is a multi-piece manifold assembly for a semiconductor processing device. The manifold assembly comprises a body comprising a first metallic material and having a bore and a base plate comprising the first metallic material and being coupled to the body. The assembly further comprises a cap comprising a second metallic material and being bonded to the base plate, the cap being configured to mount a valve thereon. The assembly also comprises an internal passage formed between the bore of the body and the cap. At least a portion of the internal passage extends through the body and the base plate without forming dead legs at a bond interface between the body and base plate.

Another aspect is an atomic layer deposition device that comprises a dispersion assembly configured to disperse gas and an inlet manifold block mounted over the dispersion assembly and having a bore, a first internal reactant line, and a second internal reactant line, the first and second internal reactant lines being in flow communication with the bore. The assembly further comprises a first reactant valve mounted on the inlet manifold block and configured to control a supply of a first reactant gas to the first internal reactant line and an inert gas valve mounted on the inlet manifold block and configured to control a supply of an inert gas to the first reactant gas valve. The assembly further comprises a second reactant valve coupled to the inlet manifold block and configured to control a supply of a second reactant gas to the second internal reactant line and a second inert gas valve mounted on the inlet manifold block and configured to control a supply of the inert gas to the second reactant gas valve.

Still another aspect is a method of distributing gases to an atomic layer deposition device having a manifold and a reactor. The method comprises routing a first reactant gas to the manifold via a first passageway having no o-rings between a first reactant valve and a manifold outlet, inhibiting the reactant gas flow, and routing an inert gas to the manifold through a second passageway upstream of the first passageway, the second passageway having no o-rings between a first inert gas valve and the first passageway.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the present invention will now be described with reference to the drawings of several preferred embodiments, which embodiments are intended to illustrate and not to limit the invention.

FIG. 1 is a schematic view showing an atomic layer deposition (ALD) device according to an embodiment of the present invention.

FIG. 2 is a schematic drawing showing one example of an intermediate dispersion element applicable to the apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic drawing showing one example of thin-film formation steps according to an embodiment.

FIG. 4 is a cross sectional view of an ALD device showing a manifold assembly coupled to an ALD reactor according to an embodiment.

FIG. 5 is a perspective view of the manifold assembly illustrated inFIG. 4.

FIG. 6 is a schematic view of gas flow paths through the manifold assembly fromFIG. 5 according to an embodiment and shows four inert gas valves, each in flow communication with a separate reactant gas valve.

FIG. 7 is a top view of the manifold assembly fromFIG. 5.

FIG. 8 is a cross-sectional view taken along lines8-8 ofFIG. 7.

FIG. 9 is an enlarged cross-sectional view taken along lines9-9 ofFIG. 7, showing flow passageways among the reactant valves, the inert gas valves, and the body of the manifold.

FIG. 10 is another embodiment of a manifold assembly having sub-components of dissimilar materials, such as aluminum and stainless steel, bonded together.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Aspects and advantages of the present invention will now be described with reference to the drawings of several preferred embodiments, which embodiments are intended to illustrate and not to limit the invention. Certain embodiments of a manifold body have one or more features. These features include an internal inert gas channel, an integral heater, no o-rings or dead zones within the precursor path, and short reactant gas passageways.

Despite the fact that ALD is prized for self-limiting reactions and thus theoretically perfectly conformal depositions without perfectly uniform conditions, various process parameters must be carefully controlled to ensure a high quality of layers resulting from ALD. It has been found that if the reactant gases are not efficiently purged, it can lead to one precursor being present when the other precursor is pulsing, leading to CVD reactions in the gas phase or on chamber/substrate surfaces instead of surface ALD reactions. Purging of the reactant gases is further complicated by the use of o-rings to assemble subcomponents of the ALD device. These o-rings create small voids commonly referred to as dead legs near the o-ring sealing surface and the gas orifice supplying the precursor. Improper evacuation of these precursors due to trapped volumes in these voids will cause particles, thus negatively impacting the ALD process. These o-rings can also be the source of leaks, either through breach of the sealing surface itself or via permeability of the o-ring material selected for high temperature and chemistry compatibility.

It is important to maintain thermal control of the precursor gas from the source (most likely a vessel carrying a solid precursor) to the wafer surface. There is usually a small window of thermal tolerance allowed (each precursor is different, but they follow the same principal). That is, by controlling thermal aspects of the solid media, vapor draw (or the amount of precursor) is managed. When the temperature is below critical set points, condensation to gas flow paths occurs causing negative process results and short maintenance intervals. When the temperature is above critical set points, “decomposition” of the media occurs and the process is in jeopardy. It is important to keep all the zones as short as possible to maintain better thermal stability.

If the manifold assembly has no thermal integration or control, the temperatures of the mixing gases may vary within the manifold assembly and lead to CVD growth. While the addition of thermal integration to the manifold assembly may inhibit undesirable CVD reactions, it may have a detrimental impact on sub-components of the manifold assembly, for example, the high speed valves. The high speed valves may not be rated for operation in an elevated temperature environment. Furthermore, dead zones along the flow path can cause the reactant gases to re-circulate upstream of the deposition chamber.

The times required to evacuate the precursor are of great importance during the ALD process. The ALD process is a “rapid fire” of precursors and purge gases. The shorter the lines and better the conductance (pumping efficiency), the shorter the process time. This is paramount to the ALD market.

FIG. 1 shows a cross section of one embodiment of the thin-film formation apparatus100 according to an embodiment of the present invention. The thin-film deposition apparatus100 includes robotics (not shown) that convey asemiconductor substrate15, which is a work piece or object to be treated, from a vacuum transfer chamber (not shown) to a reaction chamber1 via agate valve6. The reaction chamber1 comprises anupper lid2, a dispersion plate3 (a.k.a. “showerhead plate”), an exhaust duct4, a lower chamber5, the substrate-transfer gate valve6, an exhaust port7, asubstrate support8, and anelevator mechanism9 for moving thesubstrate support8 up and down.

Thesubstrate15 is loaded onto thesubstrate support8 while thesupport8 is in a loweredposition8′. Thesubstrate support8 is then moved upwards until thesemiconductor substrate15 is positioned at an appropriate distance from thedispersion plate3. Thesupport8 is located within the device and is configured to support thesubstrate15 or wafer during the deposition process. Thesupport8 may also be provided with internal or external heaters (not shown) to heat thesubstrate15 before and during processing. After thesubstrate15 is transferred from the vacuum transfer chamber to the reaction chamber1, the thin-film deposition apparatus performs a thin-film formation process in thereaction space22 by cycling, for example, reactant gases via valves31(a),31(b),31(c), and31(d) and inert gases via valves30(a),30(b),30(c), and30(d).

In certain embodiments, each reactant gas valve31(a)-(d) is in flow communication and associated with an inert gas valve30(a)-(d). Preferably, at least a portion of each reactant gas line is arranged in series with the associatedinert gas valve30. In this way, the inert gas enters the flow path of the reactant gas preferably near, but upstream from, the associatedreactant valve31 to enhance purging of the entire reactant gas line.

For example, each reactant gas valve31(a)-(d) may be a three port valve. The three port valve has two input ports in flow communication with the reactant gas source and the inert gas valve. The output port of the three port valve is in flow communication with thereaction space22. The reactant gas valves31(a)-(d) separately control flow of the reactant gases and the inert gases into thereaction space22.

In certain embodiments, each inert gas valve30(a)-(d) is a two port valve. The two port valve has one input port in flow communication with an internal inert gas channel610 (FIG. 4) and an output port in flow communication with one of the reactant gas valves31(a)-(d). The two port valve controls flow of the inert gas between the internalinert gas channel610 and an associated one of the reactant gas valves31(a)-(d). In this exemplary arrangement, the reactant gas valve31(a)-(d) is located in series with and downstream of the associated inert gas valve30(a)-(d). For gases flowing towards thereaction space22, a first location is downstream from a second location if gas at the second location flows towards the first location during substrate processing.

Each inert gas valve30(a)-(d) controls the flow of inert gas to the associated reactant gas valve31(a)-(d). The reactant gas valve31(a)-(d) controls the flow of the inert gas received from the associated inert gas valve30(a)-(d) for purging the reactant vapor line after pulsing the reactant. For example, the inert gas source(s) associated with the reactant vapor sources connected to valves31(a),31(b),31(c), and31(d) are connected to valves30(a),30(b),30(c), and30(d), respectively. These inert gas source(s) can be pressurized or not. These inert gas sources can be, for example, noble or nitrogen gas sources. The ALD control system (not shown) includes memory and processing modules, and is programmed to control these valves and other valves to selectively allow or prevent the various gases from reaching thereaction space22. For example, the flow from aninert gas valve30 enters the associated reactant gas line and may continue into the reaction chamber1 and purge the chamber of the reactant gas.

In addition to thevalves30,31 associated with the inert gases and the reactant gases, the ALD device may include a separateinert gas line54 andvalve32 connecting an inert gas source to the reaction chamber1.Inert gas valve32 provides additional inert gas to the ALD device and may be operated continuously or on a periodic basis depending on the desired substrate processing. In the illustrated embodiment, inert gas also flows to the internalinert gas channel610 via the inert channel supply line52 (FIG. 6). The inertchannel supply line52 may receive inert gas via theinert gas valve32 or a separate inert gas valve (not shown). The internalinert gas channel610 is in flow communication with the inert gas valves30(a)-(d).

TheALD device100 is configured to deposit a thin film on thesubstrate15 when thesubstrate15 is inserted in the reaction chamber1. In general, the ALD device receives a first reactant gas via one or more of the valves31(a),31(b),31(c),31(d). TheALD device100 also receives inert gas via one or more of the other valves30(a),30(b),30(c),30(d). By switching the appropriate valves, the flow of the first reactant gas is stopped and the deposition chamber and the gas lines are then purged with the inert gas from one or more valves30(a),30(b),30(c),30(d), along with the main purge flow from theinert gas line54. After the reaction chamber1 and gas lines are purged, the deposition cycle is continued with one or more of the other reactant gases. The reactants from alternated pulses react with each other only on the substrate or wafer surface to form no more than a single monolayer of the desired product in each cycle and do not react or meet in the gas phase. It should be noted that in some operational modes an increased deposition speed above one monolayer per cycle can be achieved with some sacrifice to uniformity.

In embodiments of theALD device100, two or more reactant gases are sequentially flowed (separated by periods of purging) through theALD device100 in each cycle to form materials on the wafer. Excess of each reactant gas in the reaction space is subsequently exhausted via anexhaust pipe24 after adsorbing or reacting in thereaction space22. Theexhaust pipe24 may be connected to a turbo molecular pump (TMP)50 to assist in the removal of the gases from the reaction chamber1 and provide a low pressure condition in the reaction chamber1. Furthermore, theentire ALD device100 can be pumped down to a low pressure by connecting any of the couplings on the bottom of theALD device100 to a vacuum pump (TMP50 or dry pump (DRY).

TheALD device100 includes a gasintroduction manifold assembly10. Themanifold assembly10 includes a body27 (FIG. 5), the internalinert gas channel610, and acentral bore28. Themanifold assembly10 further includes one or more of the reactant gas valves31(a),31(b),31(c),31(d), one or more of the inert gas valves30(a),30(b),30(c),30(d). Themanifold assembly10 is configured to route reactant gases entering via the reactant valves31(a),31(b),31(c),31(d) and inert gases entering via inert gas valves30(a),30(b),30(c),30(d) through the ALD device100 (seeFIG. 3). Themanifold assembly10 is further configured to selectively mix one or more of the inert gases entering via valves30(a)-(d) with one of reactant gases entering via valves31(a)-(d) during a given pulse. The resulting mixture enters the reaction chamber1. After each pulse, theALD device100 exhausts any unreacted reactant and inert gases from the reaction chamber1 via theexhaust pipe24, such as through purging. The locations of the valves shown herein are for illustrative purposes only and can be located at different locations along a gas line. Preferably the valves are located in close proximity to or on themanifold assembly10 itself to reduce the length of the gas line downstream of the valve. The reactant gas valves31(a)-31(d) may, for example, be disposed approximately 10 mm from the inlet manifold block, to provide a short and easily purged line. As will be described below, the various valves in the exemplary embodiments described herein are designated to flow a gas or a mixture of one or more gases into themanifold assembly10. However, the invention is not limited to the exemplary embodiments disclosed herein.

The order that the reactant gases are cycled through theALD device100 depends on the desired product. To minimize any interaction between one or more reactant gases prior to each gas entering the reaction chamber1, the inert gas entering via valves30(a)-(d) is periodically cycled or continuously flowed through theALD device100 between pulses of the reactant gases. In this way, the inert gases purge the lines and the reaction chamber1. As will be explained below, various reactant gases and inert gases are systematically cycled through theALD device100 so as to form a deposit on the wafer inserted through thegate valve6.

As best seen inFIG. 4, the gas-introduction manifold assembly10 is mounted over thedispersion plate3. Themanifold assembly10 is coupled to a tubular gas-introduction member11 that extends through the lid2 (seeFIG. 1). An embodiment of themanifold assembly10 is described below in connection withFIG. 1. Themember11 connects to a downstream end of themanifold assembly10 and receives reactant and inert gases from themanifold assembly10. Exemplary inert gases include nitrogen and argon gas. The deposition process utilizes the inert gases to purge and or mix with the reactant gases. Aradical source12 is shown in the illustrated embodiment connected to themanifold assembly10 via avalve16, which may be a fully-opening valve. In certain embodiments, thevalve16 is a dual action gate valve. Opening of thevalve16 introduces radicals from various gases into themanifold assembly10. Themember11 is in flow communication with a gas-dispersion portion13. Gas flowing from themember11 is diffused by the gas-dispersion portion13. The remote plasma is primarily used for chamber cleaning but may also be used for processing.

In certain embodiments, themember11 has anintermediate dispersion mechanism43.FIG. 2 is a schematic drawing showing one example of anintermediate dispersion element43. The illustratedintermediate dispersion element43 has a cylindrical shape as shown inFIG. 2 and can be attached to the downstream end or tip of the member11 (seeFIG. 1). In certain embodiments, one or more pores or slits44 in the walls of theelement43 provide diffuse flow exit paths for gas entering from themember11. Thepores44 may be located so as to evenly discharge the gas in a radial direction away from theelement43. In addition to or instead ofpores44, one or pores45 may extend through the bottom surface of theelement43 discharging gas in a vertical direction towards thedispersion plate3. Preferably, the one ormore pores45 do not line up with the pores in thedispersion plate3, for better distribution of gases across theplate3.

The cross-sectional profile of the gas-dispersion portion13 illustrated inFIG. 1 has a horn shape. In order to accommodate changes in exhaust flow through the reaction chamber1 in a short period of time, an internal capacity of the gas-dispersion portion13 is preferably small. In certain embodiments, the gas-dispersion portion13 has a flat truncated cone shape with approximately an angle of 3-30 degrees relative to the horizontal lower surface of the gas-dispersion portion13. Embodiments may include angles of 5, 10, 15, 20, 25, and values between these values, but preferably approximately 5-15 degrees, so as to more evenly distribute the dispersed gas.

In certain embodiments, a distance between the lower surface of the gas-dispersion portion13 and the gas-dispersion plate3 is approximately 2-10 mm, including 3 mm, 5 mm, 7 mm, and values between these values. Having thedispersion portion13 closer to thedispersion plate3 may more evenly distribute the gas across theplate3. In certain embodiments, the shape of internal walls of the gas-dispersion portion13 may be smooth so as to promote smooth gas flow.

In certain embodiments, aheater42 is provided in an internal wall of thedispersion portion13. Theheater42 heats gas entering thedispersion portion13. Asecond heater26 may be provided in thedispersion plate3, particularly at the peripheral edge, so as to adjust thin-film formation.

Aslit exhaust port17 is formed between a tip of the gas-dispersion portion13 and thedispersion plate3. The slit has an annular (e.g. circular) shape extending around the outer tip of thedispersion portion13. Various shapes for the exhaust port may be utilized but is preferably selected so as to minimize regions where the gas flow is hydrodynamically disrupted. For example, the shape of the exhaust port can have multiple circular-arc-shaped slits, multiple circular pores, etc. The width of the opening through the slits orpores17 may be the same as the distance between the lower surface of the gas-dispersion portion13 and the gas-dispersion plate3, or approximately between 2 mm and 5 mm.

The exhaust slit17 is communicatively connected with an upper space18. The upper space18 is formed by an upper external wall of thedispersion portion13 and the lower surface of theupper lid2. The upper space18 is communicatively connected with ashowerhead plenum14 located between a lower surface of thegas dispersion portion13 and thedispersion plate3. In certain embodiments, the distance between the upper external wall of thedispersion portion13 and the lower surface of theupper lid2 is approximately the same as the distance between the lower surface of thegas dispersion portion13 and thedispersion plate3.

Anexhaust flange19 connects to theupper lid2 and receives gas exhausted from the upper space18 and theshowerhead plenum14. Opening and closing of ashowerhead exhaust valve20 allows or prevents gas from exhausting from the upper space18 and theshowerhead plenum14.

As gas pressure drops when the gas passes through the upper space18 via theslit17, it may be make it more difficult to exhaust the gas over a short period of time between reactant pulses. Consequently, in certain embodiments, it may be advantageous to have a duct extending through theslit17 and connecting to theexhaust flange19. It has been found that an annular duct increases gas flow to theexhaust flange19 as compared to embodiments with the upper space18. This is because the internal surface area of the duct which contacts the gas is less than the surface area contacted by the gas when it flows from the upper space18. However, because theexhaust flange19 is located offset relative to the annular duct, the annular duct does not uniformly exhaust gas as compared to embodiments using the upper space18. For example, in embodiments using the upper space18, theexhaust flange19 can be located near the center of the upper space18 and receive exhausted gas uniformly.

The gas passes through the gas-dispersion portion13 and reaches theshowerhead plenum14. The gas further travels through gas-discharge ports21 in thedispersion plate3. The gas that passes through the gas-discharge ports21 reaches thereaction space22 between thesubstrate support8 and the dispersion orshowerhead plate3. The gas may then continue and reach a surface of thesubstrate15. The gas then may continue through a ring-shapedslit23 formed in the exhaust duct4 and be exhausted from anexhaust pipe24 communicatively connected with theslit23. In certain embodiments, the gas flow rate from thedispersion plate3 and to thereaction space22 is approximately 2-3 liters/sec.

By feeding radio-frequency power to thedispersion plate3 from anelectrode25, plasma can be generated between thedispersion plate3 and thesubstrate support8. For example, in situ plasma is created between thedispersion plate3 and thesubstrate support8 for plasma enhanced atomic layer deposition (PEALD) processing. Remote plasma creation is used for performing certain processes of PEALD and for periodic reaction chamber1 cleaning betweensubstrate15 processing, for example between every lot of wafers. The remote plasma is generated using an ex-situ plasma generator illustrated as the remote radical orexcited species source12. The generator may operate at, for example, a frequency of 400 kHz and be obtained from MKS Instruments located in Wilmington, Mass. The generator may be mounted on top of themanifold assembly10 or further upstream. Thevalve16 separates the remote plasma generator from themanifold assembly10. Radicals are generated in the remote plasma generator either for chamber cleaning or deposition. The radicals are allowed to flow/drift/diffuse throughout thedispersion portion13 and to the surface of thesubstrate15. Preferably theradical source12 is mounted close to the chamber1 and thevalve16 opens wide to maximize excited species survival and thus cleaning efficiency.

An RF generator for the in-situ direct plasma generation may operate at, for example, 13.56 MHz. Such an RF generator and a matching network may be obtained from ADTEC Technology Inc. located in Fremont, Calif. The matching network may be mounted on top of the reaction chamber1. A transmission line is connected between the output of the matching network and thedispersion plate3. The dispersion plate3 (FIG. 1), dispersion portion13 (FIG. 1) and upper lid ring113 (FIG. 4) are RF hot. The remainder of the conductive elements defining thereaction space22, particularly thesubstrate support8, is at ground. The direct plasma is generated only between thedispersion plate3 and thesubstrate support8.

Once processing is complete, thesubstrate support8 is lowered and thesubstrate15 can be removed from the deposition chamber via thesame gate valve6.

A control system (not shown) is configured to control the apparatus during processing of thesubstrate15. For example, the control system can include a computer control system and electrically controlled valves to control the flow of reactant and inert gases into and out of the device and the application of RF power. The control system can include modules such as a software or hardware component, such as a FPGA or ASIC, which performs certain tasks. A module may advantageously be configured to reside on the addressable storage medium of the computer control system and be configured to execute on one or more processors.

FIG. 3 shows a representative sequence for introducing gases to the reaction chamber1. In Step1 shown inFIG. 3, theshowerhead exhaust valve20 is closed. Reactant gas valve31(a) is opened to allow Gas A to enter acentral bore28 of themanifold assembly10. In this example, Gas A continues into the gas-dispersion portion13, passes through thedispersion plate3, and is supplied into thereaction space22. Gas A is exhausted from thereaction space22 through the exhaust slit23 and to theexhaust pipe24.

After Gas A is supplied for a given period of time, inStep2, the reactant gas valve31(a) for Gas A is configured to prevent gas A from entering thecentral bore28 of themanifold assembly10 and allow an inert gas flowing from the inert gas valve30(a) to enter thecentral bore28 of themanifold assembly10. At this time, depending on the particular process or chemistry involved, theshowerhead exhaust valve20 may be fully opened. The remaining Gas A is purged by the inert gas. The inert gas is introduced from the inert gas valve30(a) into the reactant gas line used for Gas A at a point upstream of reactant gas valve31(a). In this way, the inert gas flows through the reactant gas valve31(a) and flushes or purges the reactant gas lines to prevent reactant diffusion during subsequent steps. Internal inert gas channel610 (seeFIG. 4) supplies the inert gas entering the inert gas valve30(a). In certain embodiments, the internalinert gas channel610 is located within themanifold assembly10.

InStep3, the reactant gas valve31(a) is configured to prevent both reactant Gas A and the inert gas from entering thecentral bore28 of themanifold assembly10. The inert gas valve30(a) inFIG. 3 is closed instep3, but this does not have to be the case. In the illustrated embodiment, where it is desirable to halt inert gas through this channel, the three-way reactant gas valve31(a) prevents inert gas from entering thecentral bore28 of themanifold assembly10 regardless of the configuration of the inert gas valve30(a).

Gas B is introduced in thecentral bore28 of themanifold assembly10 by opening the reactant gas valve31(b). In this case, Gas B is introduced from the gas-introduction portion11 (FIG. 1) and into the gas-dispersion portion13. Gas B then continues through thedispersion plate3 and is supplied onto thesubstrate surface15. While traversing thesubstrate surface15, Gas B pulse saturates the surface of the substrate. Adsorption or reaction occurs between Gas B and the surface of the substrate as left by the previous pulse.

After passing across thereaction space22 and in a radial direction, the Gas B flows towards theexhaust pipe24 and through the exhaust slit23. Theexhaust pipe24 is configured to collect excess gas and any byproduct after the gas has saturated the wafer. In an embodiment, a region within theexhaust pipe24 is at a lower pressure than the pressure in the reaction chamber1. A negative pressure source or vacuum can be in flow communication with theexhaust pipe24 and/or exhaust slit23 to draw the gas from the reaction chamber1. Gas B is exhausted from the exhaust slit23 to theexhaust pipe24.

After a given period of time, the reactant gas valve31(b) is closed and the supply of Gas B is shut off. In the state similar to that shown inStep2, except with inert gas flowing through the Gas B channel instead of the Gas A channel, the remaining Gas B is exhausted from thevalve20. By repeating the supply of reaction Gas A and the supply of reaction Gas B as part of these four steps, each cycle deposits less than a molecular monolayer. The skilled artisan will appreciate that steric hindrance from the bulky precursors tends to block reactive sites and reduce growth rates to less than a monolayer per cycle.

Even if three kinds or more of reaction gases are used, film formation can be easily achieved by repeating steps of supplying three kinds or more of reaction gases and steps of purging respective gases.

In certain embodiments, it is possible to easily purge an inner area of thedispersion plate3 by opening or closing theshowerhead exhaust valve20. Additionally, because the degree which thevalve20 is opened or closed may be varied, complete shut-off is not required.

Also, in certain embodiments, depending on chemistry, one or more of the reactant lines (A, B, C, D) can be open at all times during the process. This may occur, for example, when the reactant gas sources act as reducing agents for the precursors delivered in pulse steps, which only react when RF power is applied.

When applying radio-frequency power to the gas-dispersion plate3, the reaction gas can also be supplied as a direct plasma gas. By providing the heater42 (FIG. 1) in the gas-dispersion portion13, it is possible to raise temperatures of the inside of thedispersion portion13. Consequently, when using organic metal materials which have low vapor pressure and easily cohere, it becomes possible to exhaust them without cohesion.

FIG. 4 is a cross sectional view showing in detail an embodiment of theALD device100. This figure does not show a substrate support or susceptor and all gas valves. Gas A reactant gas is introduced to themanifold assembly10 through valve31(a). Gas A is then introduced into afirst compartment82 of thedispersion portion13 through theslits44 in theintermediate dispersion element43. Thefirst compartment82 is defined in part by a bottom plate having slits. Gas A reactant gas passes through the slits and flows into asecond compartment81 which is above an upper surface of thedispersion plate3 having a plurality of bores (not shown). Thefirst compartment82 and thesecond compartment81 constitute a showerhead plenum.

In certain embodiments, thefirst compartment82 does not have a bottom plate and there is no clear boundary between thefirst compartment82 and thesecond compartment81. Gas A is discharged to thereaction space22 of the reaction chamber1 through the bores formed in thedispersion plate3. Thereaction space22 is located above the substrate support8 (FIG. 1). During the above process, thereaction space22 is constantly exhausted using an exhaust duct4 through anannular slit23, wherein the gas is drawn radially toward the outer periphery of thereaction space22. Theannular slit23 is located around the outer periphery of thesubstrate support8. Thegas dispersion portion13 is fixed to thedispersion plate3 via anupper lid ring113 above which an insulation plate150 is placed.

Thegas dispersion portion13 and thedispersion plate3 do not directly contact each other, and anannular gap83 is formed along the outer periphery of thegas dispersion portion13. Thisannular gap83 communicates with the exhaust flange19 (seeFIG. 1) through theupper lid plate113.

When purging the first andsecond compartments82,81, a purge gas is introduced thereto through one of the valves30(a)-(d), an associated one of the reactant gas valves31(a)-(d), themanifold assembly10, and theintermediate dispersion element13. The main purge flows from theinert gas line54 and through themanifold assembly10. Inert gas from the reactant gas valves31(a)-(d) and the inert gas valves30(a)-(d) flush or purge the lines between the reactant valves and thecentral bore28. Simultaneously, the first andsecond compartments82,81, are evacuated using theexhaust flange19 through theannular gap83. Thereaction space22 is constantly evacuated through theslit23 and the exhaust duct4.

As best seen inFIG. 5, in this example, themanifold assembly10 includes four reactant gas valves31(a)-(d), an inertchannel supply line52, and an inertmixer supply line54. Each reactant valve31(a)-(d) is paired with an inert gas valve30(a)-(d). Reactant valve31(a) is coupled to inert valve30(a). Reactant valve31(b) is paired with inert valve30(b). Reactant valve31(c) is paired with inert valve30(c). Reactant valve31(d) is paired with inert valve30(d). TheALD device100 can include greater or fewer reactant valves and inert valves depending on the configuration of theALD device100. Moreover, each reactant line may or may not be paired to one inert gas valve. For example, one or more of the reactant lines may be paired to the inert gas valves while another reactant line is not. The reactant line that is not paired to the valves could be purged by other means.

Coupling190(a) couples the reactant gas valve31(a) to a reactant source A620 (FIG. 6). Coupling190(b) couples the reactant gas valve31(b) to a reactant source B626 (FIG. 6). Coupling190(c) couples the reactant gas valve31(c) to a reactant source C632 (FIG. 6). Coupling190(d) couples the reactant gas valve31(d) to a reactant source D638 (FIG. 6).

Coupling190(f) couples the internal inert gas channel610 (seeFIG. 6) to an inert or purge gas source644 (FIG. 6). Coupling190(e) couples thecentral bore28 or inside of themanifold assembly10 with theinert gas source644 separately from the internalinert gas channel610.

In the embodiment illustrated inFIG. 5, inertchannel supply line52 and couplings190(a)-(d) provide a flow path to a valve and toward the inside of themanifold assembly10. Inertchannel supply line52 connects to the internalinert gas channel610. In the illustrated embodiment, each of the inert gas valves30(a)-(d) are located downstream of the internalinert gas channel610.Line54 provides a path to the inside of themanifold assembly10 without passing through a valve.

In the embodiment shown inFIG. 5, the couplings190(a)-(d) flow reactant gases into themanifold assembly10. Theinert gas line54 provides a passageway to flow inert gas directly to thecentral bore28. The resulting mixture (one reactant at a time with an inert gas) flows downward toward the reaction chamber1. Aninsulator plate56 lies adjacent to an insulation plate150 (FIG. 4) when assembled on theALD device100.

Themanifold assembly10 includes one ormore heater cartridges180 configured to control wall temperature. The reactant gas passing through themanifold assembly10 is heated by the manifold andheater cartridges180. Controlling the temperature of the reactant gases as they pass through themanifold assembly10 reduces the likelihood that condensation or thermal decomposition of the gas will occur. In certain embodiments, each reactant gas valve31(a)-(d) is separately heated by one ormore heater cartridges180. In the illustrated embodiment, two of the reactant valves have heaters to facilitate use of precursors with low vapor pressure (e.g., liquid or solid at standard conditions, such as ZrCl₂, HfCl₂, TMA and other metalorganics), while two do not. For example, a first set of one ormore heater cartridges180 may be located within themanifold assembly10 and near to the lines carrying reactant gas A. A second set of one ormore heater cartridges180 may be located within themanifold assembly10 and near to the lines carrying reactant gas B. The first and second sets ofheater cartridges180 may be separately controlled so as to heat gas A to a different temperature than gas B. In certain embodiments, theheater cartridges180 maintain a wall temperature up to 200° C. within themanifold assembly10. One or more thermal switches may be employed to monitor the temperature of themanifold assembly10. It will be understood that the system includes other temperature sensor and control mechanisms to maintain various components of the system at desired temperatures.

Further, the system may maintain a different temperature for a first pair ofvalves30,31 and a second temperature for a second set ofvalves30,31 depending on the desired processing. While the illustrated embodiment contemplates heater cartridges driven by temperature sensor(s) defining a single zone for temperature control of the monolithic ALD inlet manifold, the illustrated embodiment can also be adapted for separated zone control for each precursor within the ALD manifold. For example, in the illustrated case of 4 precursors with separate manifold paths, five zones can be provided for separate thermal control of the flow path for each precursor the center hub and each of the four precursor lines (including valves) are treated as separate zones. To facilitate thermal separation of zones, the hub could be manufactured with a thermal air break limiting the mechanical and thermal connection between, for example, thebody27 and a base plate606 (seeFIG. 10) to small spot protrusions around the precursor gas inlet apertures. Additional heaters and thermocouples to monitor thermal control would be employed. Advantageously, temperatures of the flow paths upstream of the mixing point (e.g., the central bore) can be separately tuned for each reactant to minimize coating of the lines, whether by condensation, reaction or adsorption, and thus minimize clogging and/or downstream contamination.

FIG. 6 is a schematic view of gas flow paths through themanifold assembly10 illustrated inFIG. 5 and shows four inert gas valves31(a)-(d), each in flow communication with separate reactant gas valves30(a)-(d). Themanifold assembly10 includes an internalinert gas channel610 in flow communication with the four inert gas valves30(a)-(d).FIG. 6 further illustrates the source for each reactant and inert gas. The reactant sources may represent gas containers, bubblers or other vaporizers, depending on whether reactants are solid, liquid, or gas under standard conditions. Additional valves (not shown) associated with the reactant and inert gas sources may be located outside of themanifold assembly10.

Gas A flows from itssource620 and throughline622 before reaching reactant valve31(a). Reactant gas valve31(a) may be configured to allow or prevent flow of gas A throughline624 and into thecentral bore28 of themanifold assembly10 depending on the desired processing step. Gas B flows from itssource626 and throughline628 before reaching reactant valve31(b). Reactant gas valve31(b) may be configured to allow or prevent flow of gas B throughline630 and into thecentral bore28 of themanifold assembly10 depending on the desired processing step.

Gas C flows from itssource632 and throughline634 before reaching reactant valve31(c). Reactant gas valve31(c) may be configured to allow or prevent flow of gas C throughline636 and into thecentral bore28 of themanifold assembly10 depending on the desired processing step. Gas D flows from itssource638 and throughline640 before reaching reactant valve31(d). Reactant gas valve31(d) may be configured to allow or prevent flow of gas D throughline642 and into thecentral bore28 of themanifold assembly10 depending on the desired processing step. The illustrated four reactant valve embodiment is exemplary and more or less reactant valves could be used.

The inert gas flows from source644 (which may include multiple gas containers) and through the inertchannel supply line52 before reaching the internalinert gas channel610. The internalinert gas channel610 is preferably located within themanifold assembly10. By including theinert gas channel610 within themanifold assembly10, maintenance proficiency is enhanced. Advantageously, themanifold assembly10 may be tested on a bench prior to re-assembly onto the reactor. With theinert gas channel610 included in themanifold assembly10, thermal control of the inert gas is more uniform with the precursor gas since the inert gas and the precursor gas are fed through the same thermal mass ormanifold assembly10.

When the inert gas channel is located outside the manifold and inside the reactor top, additional o-rings are required in the chamber. These additional o-rings can affect vacuum integrity of the reactor. Cleaning may also be more complicated since the entire reactor is disassembled to access an inert gas channel that is located within the reactor.

The internalinert gas channel610 is further in flow communication with one or more of the inert gas valves30(a)-(d). In the exemplary embodiment illustrated inFIG. 6, the internalinert gas channel610 is in flow communication with four inert gas valves30(a)-(d).

The inert gas flows from the internalinert gas channel610 and throughline646 before reaching inert gas valve30(a). In certain embodiments, the inert gas valve30(a) is a two port valve. The two port valve controls flow of the inert gas between the internalinert gas channel610 and the reactant gas valve31(a). The two port valve has one input port in flow communication with the internalinert gas channel610 and an output port in flow communication with reactant gas valve31(a) vialine648. In this way, the inert gas valve30(a) may be configured to allow or prevent flow of inert gas betweenline646 andline648.

Reactant gas valve31(a) is in flow communication withline648. In addition to allowing or preventing reactant gas A from reaching thecentral bore28 of themanifold assembly10 fromline622 as described above, the reactant gas valve31(a) is further configured to allow or prevent flow of inert gas throughline624 and into thecentral bore28 of themanifold assembly10. Thus, the reactant gas valve31(a) may be configured to separately allow or prevent the inert gas and the reactant gas A from enteringline624.

In a preferred embodiment, reactant gas valve31(a) is a three port valve. A first port of reactant gas valve31(a) is in flow communication withline622 and receives reactant gas A. A second port of reactant gas valve31(a) is in flow communication withline648 and receives an inert gas. A third or exit port for reactant gas valve31(a) is in flow communication with thecentral bore28 of themanifold assembly10 vialine624.

The inert gas flows from the internalinert gas channel610 and throughline650 before reaching inert gas valve30(b). In certain embodiments, the inert gas valve30(b) is a two port valve. The two port valve controls flow of the inert gas between the internalinert gas channel610 and the reactant gas valve31(b). The two port valve has one input port in flow communication with the internalinert gas channel610 and an output port in flow communication with reactant gas valve31(b) vialine652. In this way, the inert gas valve30(b) may be configured to allow or prevent flow of inert gas betweenline650 andline652.

Reactant gas valve31(b) is in flow communication withline652. In addition to allowing or preventing reactant gas B from reaching thecentral bore28 of themanifold assembly10 fromline628 as described above, the reactant gas valve31(b) is further configured to allow or prevent flow of inert gas throughline630 and into thecentral bore28 of themanifold assembly10. Thus, the reactant gas valve31(b) may be configured to separately allow or prevent the inert gas and the reactant gas B from enteringline630.

In a preferred embodiment, reactant gas valve31(b) is a three port valve. A first port of reactant gas valve31(b) is in flow communication withline628 and receives reactant gas B. A second port of reactant gas valve31(b) is in flow communication withline652 and receives an inert gas. A third or exit port for reactant gas valve31(b) is in flow communication with thecentral bore28 of themanifold assembly10 vialine630.

The inert gas flows from the internalinert gas channel610 and throughline654 before reaching inert gas valve30(c). In certain embodiments, the inert gas valve30(c) is a two port valve. The two port valve controls flow of the inert gas between the internalinert gas channel610 and the reactant gas valve31(c). The two port valve has one input port in flow communication with the internalinert gas channel610 and an output port in flow communication with reactant gas valve31(c) vialine656. In this way, the inert gas valve30(c) may be configured to allow or prevent flow of inert gas betweenline654 andline656.

Reactant gas valve31(c) is in flow communication withline656. In addition to allowing or preventing reactant gas C from reaching thecentral bore28 of themanifold assembly10 fromline634 as described above, the reactant gas valve31(c) is further configured to allow or prevent flow of inert gas throughline636 and into thecentral bore28 of themanifold assembly10. Thus, the reactant gas valve31(c) may be configured to separately allow or prevent the inert gas and the reactant gas C from enteringline636.

In a preferred embodiment, reactant gas valve31(c) is a three port valve. A first port of reactant gas valve31(c) is in flow communication withline634 and receives reactant gas C. A second port of reactant gas valve31(c) is in flow communication withline656 and receives an inert gas. A third or exit port for reactant gas valve31(c) is in flow communication with thecentral bore28 of themanifold assembly10 vialine636.

The inert gas flows from the internalinert gas channel610 and throughline658 before reaching inert gas valve30(d). In certain embodiments, the inert gas valve30(d) is a two port valve. The two port valve controls flow of the inert gas between the internalinert gas channel610 and the reactant gas valve31(d). The two port valve has one input port in flow communication with the internalinert gas channel610 and an output port in flow communication with reactant gas valve31(d) vialine660. In this way, the inert gas valve30(d) may be configured to allow or prevent flow of inert gas betweenline658 andline660.

Reactant gas valve31(d) is in flow communication withline660. In addition to allowing or preventing reactant gas D from reaching thecentral bore28 of themanifold assembly10 fromline640 as described above, the reactant gas valve31(d) is further configured to allow or prevent flow of inert gas throughline642 and into thecentral bore28 of themanifold assembly10. Thus, the reactant gas valve31(d) may be configured to separately allow or prevent the inert gas and the reactant gas D from enteringline642.

In a preferred embodiment, reactant gas valve31(d) is a three port valve. A first port of reactant gas valve31(d) is in flow communication withline640 and receives reactant gas D. A second port of reactant gas valve31 (d) is in flow communication withline660 and receives an inert gas. A third or exit port for reactant gas valve31(d) is in flow communication with thecentral bore28 of themanifold assembly10 vialine642.

The terms “prevent” and “allow” are relative terms and are not limited to the sealing off of gas flow or to permitting full flow. For example, reactant gas valve31(a) is configured to allow reactant gas flow when reactant gas flowing through the valve is increased. Similarly, reactant gas valve31(a) is configured to prevent reactant gas flow when reactant gas flowing through the valve is decreased. Further, the lengths of the lines illustrated inFIG. 6 are for ease of identification and may shorter or longer depending on the desired configuration. In certain embodiments, it may be preferred to shorten one or more lines to reduce the amount of non-reacted reactants to be purged from themanifold assembly10. In fact, the “lines” ofFIG. 6 within themanifold assembly10 are all machined channels within the central block and/or appended plates, such that the distances between the valves and the reaction chamber are minimal, reducing purge times, as will be appreciated fromFIGS. 4-5 and7-10.

An inertmixer supply line54 couples thecentral bore28 or inside of themanifold assembly10 with theinert gas source644 separately from the internalinert gas channel610.Line54 provides a path to thecentral bore28 without passing through a valve. In certain embodiments, avalve662 controls flow of the inert gas entering themanifold assembly10 fromline54.

FIG. 7 is a top view of themanifold apparatus10 fromFIG. 5 illustrating reactant gas valves31(a)-(d) and inert gas valves30(a)-(d) coupled to thecentral body27 of themanifold assembly10. Themanifold assembly10 is configured to route reactant gases entering via couplings190(a)-(d) and inert gas entering via coupling190(e) to thecentral bore28 of themanifold assembly10. The coupling190(a) is in flow communication with reactant gas valve31(a) vialine622. The coupling190(b) is in flow communication with reactant gas valve31(b) vialine628. The coupling190(c) is in flow communication with reactant gas valve31(c) vialine634. The coupling190(d) is in flow communication with reactant gas valve31(d) vialine640. The coupling190(e) is in flow communication with thecentral bore28 of themanifold assembly10 vialine54.

Themanifold assembly10 may route a single gas or multiple gases at the same time to thecentral bore28 of themanifold assembly10 during a given pulse. Preferably, in ALD mode, one reactant gas is mixed with inert gas in thebore28. The resulting mixture enters the deposition chamber1 (FIG. 1). After each pulse, the ALD exhausts any unreacted reactant and inert gases from the deposition chamber via theexhaust pipe24 and from the showerhead assembly via the showerhead exhaust valve20 (FIG. 1), such as through purging.

Inert gas may continually flow to thecentral bore28 of themanifold assembly10 vialine54 during processing, intermittingly, or only during purge operations. As discussed above, inert gas may also flow to the internalinert gas channel610 via the inert channel supply line52 (FIG. 6) within themanifold assembly10. The internalinert gas channel610 is in flow communication with the inert gas valves30(a)-(d).

The inert gas valves30(a)-(d) attach directly to thebody27 of themanifold assembly10. As seen inFIGS. 8 and 9, each reactant gas valve31(a)-(d) may be mounted on thebody27 using a spacer block700(a)-(d) which attaches to thebody27. The spacer blocks700(a)-(d) are provided with openings and screw holes which mate with the reactant gas valves31(a)-(d). The spacer blocks700(a)-(d) ease manufacturing of themanifold assembly10. Spacer block700(a) is associated with reactant gas valve31(a) and provides flow paths between thebody27 of themanifold assembly10 and the reactant gas valve31(a). Spacer block700(b) is associated with reactant gas valve31(b) and provides flow paths between thebody27 of themanifold assembly10 and the reactant gas valve31(b). Spacer block700(c) is associated with reactant gas valve31(c) and provides flow paths between thebody27 of themanifold assembly10 and the reactant gas valve31(c). Spacer block700(d) is associated with reactant gas valve31(d) and provides flow paths between thebody27 of themanifold assembly10 and the reactant gas valve31(d).

FIG. 8 is a cross-sectional view taken along lines8-8 ofFIG. 7, whileFIG. 9 is a cross-sectional view taken along lines9-9 ofFIG. 7. Each spacer block700(a)-(d) provides a portion of the gas routing paths to and from the associated reactant gas valve31(a)-(d). The gas routing paths illustrated inFIGS. 8 and 9 correspond to lines described with reference toFIG. 6. An entire line described inFIG. 6 may represent an entire passageway in a single component of themanifold assembly10 or portions of passageways in multiple components of themanifold assembly10. For example,line652 illustrated inFIGS. 6 and 8 corresponds to at least portions of passageways in both thebody27 of themanifold assembly10 and in the spacer block700(b).Line660 illustrated inFIGS. 6 and 8 corresponds to at least portions of passageways in thebody27 of themanifold assembly10 and in the spacer block700(d).

Thebody27 in the illustrated embodiment has a tubular shape with acentral bore28. Thebody27 includes anentrance612 and anexit614. Thecentral bore28 can have a lower portion having a cylindrical shape and an upper portion having a conical shape. The cross-sectional area in the region of theentrance612 is preferably greater than the cross-sectional area of theexit614. In some embodiments, the cross-sectional flow area of thecentral bore28 gradually decreases as the mixture migrates towards theexit614 and forms a tapered or “funnel” passage.

In certain embodiments, at least a portion of the inner surface of thebody27 has a conical shape which reduces the open cross-section area through thebody27 as the mixture flows towards theexit614. Thebody27 further includes attachment holes on the downstream or bottom surface for attaching themanifold assembly10 to the showerhead plate of the reaction chamber1.

In the illustrated embodiment, each spacer block700(a)-(d) has three distinct passageways connected to the two input ports and the single output port of the associated reactant gas valve31(a)-(d). For example, a first passageway orline652 in both the spacer block700(b) and thebody27 of themanifold assembly10 connects the output port of the inert gas valve30(b) to one of the two input ports for the reactant gas valve31(b). The second passageway orline628 connects coupling190(b) to the other input port for the reactant valve31(b). The third passageway orline630 connects the output port of the reactant gas valve31(b) with thecentral bore28 of themanifold assembly10. With respect to reactant gas valve31(d), a first passageway orline660 in both the spacer block700(d) and thebody27 of themanifold assembly10 connects the output port of the inert gas valve30(d) to one of the two input ports for the reactant gas valve31(d). The second passageway orline640 connects coupling190(d) to the other input port for the reactant valve31(d). The third passageway orline642 connects the output port of the reactant gas valve31(d) with thecentral bore28 of themanifold assembly10. The inert gas valves30(a)-(d) are partially obstructed from view by the reactant gas valves31(a)-(d) inFIG. 7.

FIG. 9 is an enlarged cross-sectional view taken along lines9-9 ofFIG. 7, showing reactant valves31(a),31(c) and inert gas valves30(a),30(c) connected to thebody27 of themanifold assembly10. Referring toFIGS. 7 and 9, spacer block700(a) is associated with reactant gas valve31(a) and provides flow paths between thebody27 of themanifold assembly10 and the reactant gas valve31(a). Spacer block700(c) is associated with reactant gas valve31(c) and provides flow paths between the body of themanifold assembly10 and the reactant gas valve31(c). A first passageway orline648 in both the spacer block700(a) and thebody27 of themanifold assembly10 connects the output port of the inert gas valve30(a) to one of the two input ports for the reactant gas valve31(a). The second passageway orline622 connects coupling190(a) to the other input port for the reactant valve31 (a). The third passageway orline624 connects the output port of the reactant gas valve31(a) with thecentral bore28 of themanifold assembly10. With respect to reactant gas valve31(c), a first passageway orline656 in both the spacer block700(c) and thebody27 of themanifold assembly10 connects the output port of the inert gas valve30(c) to one of the two input ports for the reactant gas valve31(c). The second passageway orline634 connects coupling190(c) to the other input port for the reactant valve31(c). The third passageway orline636 connects the output port of the reactant gas valve31(c) with thecentral bore28 of themanifold assembly10.

Passageway orline654 connects the input port of the inert gas valve30(c) with the internalinert gas channel610. Passageway orline646 connects the input port of the inert gas valve30(a) with the internalinert gas channel610.

Referring toFIGS. 8 and 9, reactant gas enters thecentral bore28 of themanifold assembly10 vialines624,630,636,642 preferably off center from acenterline702 so as to swirl the gas within thecentral bore28 to enhance mixing. Swirling gas may promote mixing of the reactant gas with an inert gas and/or another reactant gas depending on the desired product. The gas mixture circles around inside the tubular body as the mixture migrates towards the deposition chamber1.

In certain embodiments, one or more of thebody27, spacer700(a)-(d), and valve30(a)-(d),31(a)-(d) components are stainless steel or other metallic material. With stainless steel, themanifold assembly10 need not include o-rings, resulting in no dead zones. Advantageously, the lines or passageways are integrally formed within a chemically resistant metal block orbody27. In certain embodiments, the inert andreactant valves30,31 are stainless steel and commercially available from Swagelok Co. of Salon, Ohio. In a preferred embodiment, the Swagelok two port inert gas valves30(a)-(d) are identified as part number 6LVV-MSM-ALD3T-W2-P-CS and the three port reactant gas valves31(a)-(d) are identified as part number 6LVV-MSM-ALD3T-W3-P-CS. Each of themetal valves30,31 may be sealed against the metal and preferablystainless steel spacer700 andbody27 of the manifolds with metal seals. In certain other embodiments, one or more components of themanifold assembly10 are made from a ceramic material.

FIG. 9 further illustrates various metal seals located between surfaces of mating components. Of course, more or less metal seals could be used depending on, for example, the materials, tolerances, operating pressures, and gases associated with the mating components. Further, in certain embodiments, one or more components may be combined into a single component and therefore render any seals between the combined components unnecessary. For example, the spacer block700(a)-(d) and associated reactant gas valve31(a)-(d) could be combined into a single component and obviate the need for seals between the combined components. Further, the spacer block700(a)-(d) associated with a reactant gas valve may extend beyond the side of the reactant gas valve so as to form a spacer for the adjacent inert gas valve (seeFIG. 10). Alternatively, the reactant gas valve and the inert gas valve associated with the reactant gas valve may have separate spacers.Conventional seals900 made from polymeric materials, such as for o-rings, are also employed to seal themanifold assembly10 against the showerhead assembly.

FIG. 10 schematically illustrates another embodiment of amanifold assembly10 wherein the spacer blocks comprise sub-components of dissimilar materials, such as aluminum and stainless steel, bonded between the reactant gas valve31(a) and its associated inert gas valve30(a) and thebody27 of themanifold assembly10. For this embodiment, reactant gas valve31(a) and inert gas valve30(a) are illustrated while reactant gas valves31(b)-(d) and inert gas valves30(b)-(d) are not. However, the following description applies equally to the other three pairs of reactant gas valves and associated inert gas valves30(b),31(b);30(c),31(c);30(d),31(d).

In this preferred embodiment, the valves31(a),30(a) are made of a stainless steel, for example 316 SS. Stainless steel advantageously increases the durability of the valves over lesser strength metals. Thebody27 of themanifold assembly10 is made from an aluminum or similar material and provides high thermal conductivity. Advantageously, aluminum is a relative light metal and provides enhanced thermal distribution in comparison to stainless steel. Alternatively, thebody27 may be made from 316 stainless steel. Of course other materials may be used for thebody27.

As illustrated inFIG. 6, many internal passageways within themanifold assembly10 are shared between components. An interface between connecting passageways in different parts conventionally employs recesses in the mating surfaces to accommodate an o-ring or other sealing device900 (FIG. 9). The recesses and associated seals increase the likelihood of forming a dead zone at the interface. It is advantageous to have fewer recessed or embedded seals, o-rings, and any resulting dead zones along the flow paths between thecentral bore28 of themanifold assembly10 and the reactant and inert gas valves. Such dead zones would provide gaps or voids which inhibit complete purge of the flow paths. An incompletely purged first reactant gas may undesirably react with a second reactant gas at the site of the void or at a location along the flow path to which the first reactant can diffuse.

It has been found that by reducing the number of intermediary interfaces located between thebody27 and thevalves30,31, the number of seals is reduced along with the susceptibility for forming dead zones. Where interfaces must occur, advanced fabrication techniques may be utilized to minimize the formation of dead zones at the interfaces. These fabrication techniques include electron beam welding, employing metal seal technology, explosion bonding, and the like. One or more of these techniques may be used to manufacture themanifold assembly10.

In this preferred embodiment, one or more members are sandwiched between thebody27 and the valves31(a),30(a). In the illustrated embodiment, analuminum base plate606 and astainless steel cap608 connect thebody27 to the valves30(a),31(a). Thebase plate606 andcap608 further connect to each other. Preferably, thebase plate606 andcap608 are connected together before being connected to thebody27. In certain embodiments, thebase plate606 and thecap608 are attached together using an explosion bonding technique known in the art. Explosion bonding fuses the dissimilar materials of thebase plate606 andcap608 to provide a seal-free interface therebetween.

Preferably, thebase plate606 is made from the same material as thebody27 to simplify their attachment to each other. In this exemplary embodiment, both are made from aluminum. Before attaching an assembly of thebase plate606 andcap608 to thebody27, the internalinert gas channel610 is machined in thebody27. A surface of thebase plate606 forms an outer surface of the internalinert gas channel610. The illustrated shape and size of the internalinert gas channel610 is only exemplary and may have a different shape and size. Further, the location of the internalinert gas channel610 is only exemplary and may be moved from the illustrated location within thebody27.

The explosion bondedbase plate606 andcap608 are attached to the outer surface of thebody27. An energy beam welding method may be employed to attach thebase plate606 to thebody27. For example, a laser beam or electron beam may be used and provide a highly focused beam of energy to weld the materials together. In certain embodiments, thebase plate606 is electron beam welded to thebody27.

The valves are then connected to thecap608. In certain embodiments, a metal seal is employed to form a seal between thevalves30,31 and thecap608. Metal seals, as opposed to polymeric o-rings, have increased chemical resistance. In certain embodiments, a W-shaped metal seal is employed at the interface between thevalves30,31 and thecap608. Metals seals are also advantageous due to their ability to withstand higher loads without excessively deforming as compared to polymeric o-rings. The metal seal may be coated or not.

Once assembled, the inert gas flows from the internalinert gas channel610 and throughline646 before reaching inert gas valve30(a). Advantageously, the bond between thebody27 and thebase plate606 is an electron beam weld having no separate seals. The bond between thebase plate606 and thecap608 is an explosion bond having no separate seals. A releasable metal seal is employed between the valves30(a),31(a) and thecap608 allowing removal of the valves30(a),31(a) for inspection, cleaning, and maintenance.

The inert gas valve30(a) output port is in flow communication with reactant gas valve31(a) vialine648.Line648 is preferably not shared among components of the internalinert gas channel610 and requires no seals besides at the inlet and outlet for theline648. Preferably, the seals sealing the exit fromline646, the inlet toline648, the outlet fromline648, the exit fromline622, and the inlet toline624 are metal. Advantageously, the use of metal seals can increase the seal life over conventional polymeric seals and enhance contamination exclusion due to their high chemical resistance.

Reactant gas valve31(a) is in flow communication withline648. In addition to allowing or preventing reactant gas A from reaching thecentral bore28 of themanifold assembly10 fromline622, the reactant gas valve31(a) is further configured to allow or prevent flow of inert gas throughline624 and into thecentral bore28 of themanifold assembly10. Thus, the reactant gas valve31(a) may be configured to separately allow or prevent the inert gas and the reactant gas A from enteringline624.

In a preferred embodiment, reactant gas valve31(a) is a three port valve. A first port of reactant gas valve31(a) is in flow communication withline622 and receives reactant gas A. A second port of reactant gas valve31(a) is in flow communication withline648 and receives an inert gas. A third or exit port for reactant gas valve31(a) is in flow communication with thecentral bore28 of themanifold assembly10 vialine624.

Controlling the machining tolerances of thebase plate606 andcap608 can aid in aligning a first portion of a line on a first side of an interface with a second portion of that same line on a second side of the same interface thereby reducing recirculation or voids within themanifold assembly10. Controlling the surface finish and flatness on the mating surfaces of the sub-components of themanifold assembly10 can aid in sealing adjacent sub-components. In certain embodiments, a 16 to 32 micro finish surface is maintained on the sealing surfaces.

The control system controls one or more of thevalves30,31 to selectively allow or prevent one or more gases from reaching thecentral bore28 of themanifold assembly10. Advantageously, the embodiments of themanifold assembly10 reduce the need for conventional seals at interfaces between components of themanifold assembly10. Reducing the number of conventional seals decreases the chance of forming dead legs or zones. For ALD operation, reducing dead legs reduces the duration of purging needed to avoid interaction of reactants upstream of the reaction space. Such interaction could lead to contamination or non-uniformities in the deposition on substrates. Where interfaces must occur, advanced fabrication techniques may be employed to minimize the formation of dead zones. These fabrication techniques include electron beam welding, employing metal seal technology, explosion bonding, and the like. Themanifold assembly10 further employsdiscrete heaters180 to individually control the temperature of the various gases entering thecentral bore28 of themanifold assembly10.

Although the present invention has been described in terms of a certain preferred embodiments, other embodiments apparent to those of ordinary skill in the art also are within the scope of this invention. Thus, various changes and modifications may be made without departing from the spirit and scope of the invention. For instance, various components may be repositioned as desired. Moreover, not all of the features, aspects and advantages are necessarily required to practice the present invention.

Claims (12)

1. An atomic layer deposition (ALD) device, comprising:

a dispersion assembly configured to disperse gas;

an inlet manifold block mounted over the dispersion assembly and having a bore, an internal inert gas channel, a first internal reactant line, and a second internal reactant line, the first and second internal reactant lines being in flow communication with the bore;

a first reactant valve mounted on the inlet manifold block and configured to control a supply of a first reactant gas to the first internal reactant line;

a first inert gas valve mounted on the inlet manifold block and configured to control a supply of an inert gas from the internal inert gas channel to the first reactant valve;

a second reactant valve coupled to the inlet manifold block and configured to control a supply of a second reactant gas to the second internal reactant line; and

a second inert gas valve mounted on the inlet manifold block and configured to control a supply of the inert gas from the internal inert gas channel to the second reactant valve.

2. The ALD device ofclaim 1 further comprising a controller configured to control the first reactant valve and the second reactant valve.

3. The ALD device ofclaim 1, wherein the controller alternates the supply of the first reactant gas and the second reactant gas to the bore.

4. The ALD device ofclaim 1, wherein the dispersion assembly comprises a showerhead assembly having an exhaust passage.

5. The ALD device ofclaim 1 further comprising a spacer block, the spacer block being disposed between the first reactant valve and the inlet manifold block.

6. The ALD device ofclaim 5, wherein the spacer block comprises a base plate and a cap.

7. The ALD device ofclaim 1 further comprising a spacer block, the spacer block being disposed between the first inert gas valve and the inlet manifold block.

8. The ALD device ofclaim 1, wherein the distance between the first reactant valve and the inlet manifold block is about 10 mm.

9. The ALD device ofclaim 8, wherein the first internal reactant line is angled relative to a centerline through the conically shaped bore so as to promote swirling of the first reactant gas in the bore.

10. The ALD device ofclaim 1, wherein at least a portion of the bore has a conical shape.

11. The ALD device ofclaim 1, wherein the first internal reactant line has no o-rings between the first reactant valve and the inlet manifold block.

12. The ALD device ofclaim 1, wherein the first and second reactant valves and the first and second inert gas valves are rated for operation at a temperature of at least 200° C.

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